1. Field of the Invention
This invention relates to the field of glycols and more particularly, to processes for obtaining glycols from the hydrolysis of halohydrins and dihaloalkanes.
2. Description of the Prior Art
Numerous processes are known for obtaining glycols from the hydrolysis of halohydrins and dihaloalkanes (viz., U.S. Pat. Nos. 1,442,386; 1,594,608; 1,626,398; 1,695,250; 1,709,605; 1,895,517; 1,996,193; 2,047,811; 2,181,297; and, 2,838,574). These processes employ alkali metal hydroxides and/or alkali metal carbonates in the hydrolysis media in order to provide a receptor for the haloacid which is generated by the reaction. The overall reaction (illustrated for the production of 1,3-propanediol from propylene chlorohydrin using aqueous sodium hydroxide) is as follows: EQU ClCH.sub.2 CH.sub.2 CH.sub.2 OH+NaOH.fwdarw.HOCH.sub.2 CH.sub.2 CH.sub.2 OH+NaCl
In this reaction, one mole of alkali metal hydroxide must be used for each mole of halohydrin hydrolyzed to glycol and when dihalide is employed as the glycol precursor, two moles of alkali metal hydroxide must be employed. Such a substantial requirement of alkali metal hydroxide (or alkali metal carbonate) places these synthetic procedures for obtaining glycols at a considerable competitive disadvantage compared to other synthetic procedures for obtaining glycols. Moreover, since the haloacid produced by the prior art processes is completely neutralized, a valuable reagent for preparing additional quantities of halohydrin (viz., U.S. Pat. No. 3,277,187) is lost.
Accordingly, there has heretofore existed a need for an economically efficient process for hydrolyzing halohydrins and dihaloalkanes to the corresponding glycols which does not require the consumption of alkali metal hydroxides and/or alkali metal carbonates and which permits recovery of the haloacid by-product.